March 11

Sarah Robertson

Betta Macrostoma Care Guide: Tank Setup, Size, Diseases & Breeding

Betta Splendens are incredibly interesting fish that come in numeric size, shapes, colors, and finnage. There are many varieties of betta Splendens, and one of the more interesting types is Betta Macrostoma, also known as the Brunei Beauty.

The betta Macrostoma is a labyrinth fish, meaning unlike most aquarium fish they have the capability to take oxygen from the atmospheric level as well as from their gills. Unlike any other bettas, these stunning fish are mouthbrooders because of their huge jaw and mouth, which earned them their name.

These beautiful fish come in a variety of colors such as red, orange, brown and even yellow with black and white markings. They can be found in tropical climates and are very hardy fish.


Betta Macrostoma comes from the Brunei, Malaysia and Indonesia. Although these fish are uncommon in the wild, they may be found in limited numbers in certain bodies of water. 

These are soft water fish and were once labelled as vulnerable fish and were added to the IUCN Red list due to overexploitation. However, the species were removed from this list in 2009 because their population is stable enough due to conservation efforts.


These are short bodied fish that have a very big head and mouth compared to other bettas, which earned them their name. They can grow up to 4 inches (10 cm).

Tank Requirements

This variety of betta Splendens can grow up to 4 inches in length, a 20 gallon is absolutely fine for a single adult Betta Macrostoma and you would want to increase your tank size if you plan to house multiple fish together. The aquarium should have a good filtration system as these fish are messy eaters.   Water parameters such as pH and temperature should be tested on a regular basis. Bettas need acidic water.

The tank's water must have a pH of 6 to 7 and temperatures should be 70°F to 75°F. According to certain research, Betta Macrostoma can live for up to five years if properly cared for. When cleaning a fish tank, special attention must be paid to Betta Macrostoma since they are excellent at slipping through the tiniest of cracks. 

How Often Do You Have to Clean the Tank?

The fish tank must be cleaned every week. This is because the Betta Macrostoma will release a lot of ammonia in the water and this can build up very quickly. Make sure that you don't move the Betta Macrostoma around much because this fish is very sensitive to changes in water movement and oxygen levels.

Betta Macrostoma Care Guide 1

Tank Decor

As for tank décor, this fish will not destroy the live plants nor the aquarium ornaments. It is a timid fish and it will usually hide in the caves or under the tank décor when it is scared. The Betta Macrostoma will appreciate a well planted aquarium with some hiding spaces.

The fish tank should be decorated with driftwood and plants to give the fish a sense of security and to let them claim their own territories. The live plants will make the aquarium look more attractive and it will give your fish some places to hide when they are scared of other fish.

They mostly prefer a thick and dense planting. Unlike other bettas these types are best raised in pairs. These fishes don't have long and wavy fin and for this reason, they don't need as much open swimming space as other bettas. Betta Macrostoma are very good jumpers, unlike all other bettas, they can escape out of the tank in seconds. A good hood with a tight seal is also important to keep your fish in the aquarium.


Betta Macrostoma are very sensitive to changes in environment and this includes water temperature, acidity, and oxygen levels. Therefore, you should keep the tank very stable. The most common illness you are likely to find is

  • Fungal Infection: Fungal infection is a disease that causes irritation and damage to the fish's skin. It looks like there are some white plaques on the fish's body and fins. The best treatment for this is adding salt to your tank or increasing the water quality in the quarantine tank. You can also add an antibiotic to your tank so that it is ingested through the fish's system. Fungal infection can be dangerous if they spread to the fish's gills.
  • Dropsy: It is the swelling in the body of a betta fish. This can be caused by a bacterial infection or a parasitic infection from flukes, worms, or Hexamita. It can also be caused by poor nutrition or mishandling of the fish while catching it. One sign is when the fish's scales stick out laterally. Dropsy can also be caused by an injury, but it is most common to see this symptom with fish that are stressed. For example, if the betta's tank water is changed or it is moved to a different environment. If the environment is too warm or if there are toxins in the water. For treatment, you should change half of the water in the aquarium every day and add some aquarium salt.
  • Swim Bladder Disorder: This disorder occurs when the betta fish has an inflamed or deformed swim bladder. The fish will not be able to control its buoyancy and it will not be able to swim and will have a difficult time maintaining a particular level in the water. You can verify this disorder by checking if the fish has a curved spine, swollen abdomen, or is bloated. For treatment, you should feed the fish a lot of foods that promote digestion and add some weight to its body.
  • Fin Rot: This is an infectious disease that causes the fins to deteriorate and get eaten away by bacteria. The easiest treatment for this is adding aquarium salt to your tank and in a quarantine tank as it can be caused by poor water quality. You can also add an antibiotic to your water so that it is ingested through the betta's system.
  • Gill Flukes: These are small parasites that attach themselves to the fishes’ gills. It damages the fish because it sucks up the fish's blood and prevents it from breathing. Fish that have been infected by gill flukes will show some swollen gills and it will not be able to breathe. You can treat this by ensuring the water has a balanced PH and temperature.

These are all common infectious diseases that are likely to affect your Betta Macrostoma, but there are others. If you notice any changes in its behavior or appearance then it would be best to look it up or take it to a nearby aquarium shop for advice.

Betta Macrostoma Care Guide

Betta Macrostoma Breeding

The Betta macrostoma, often known as the Brunei beauty, is one of the most popular mouthbrooding wild betta fish. Unlike any other betta fish, Betta Macrostoma are hard to breed. Water quality and breeding tank setup must be excellent.

 If you want to breed them, you'll need to distinguish between the males and females. It's difficult to tell a Betta Macro stoma’s gender when they're still young, but you can tell when they get older. The female Betta Macrostoma will grow larger in size and have a slimmer body shape.

The male Betta Macrostoma will have larger fins and will also have an extended finnage under its stomach. There are certain environments that will make your Betta Macrostoma ready to breed. The water should be around 70°F, the water should also be relatively soft.

Breeding Process

The breeding process starts by the Male’s courtship display. He will puff out his fins and try to entice the female to spawn with him. When males reach adult proportions, their courtship displays improve.

When they perform the display, they appear to be far larger, which impresses the female betta. This process helps the female betta to become ready for spawning. The female's temperament changes dramatically after spending almost a day or two dormant.

She loses all of her ruddy-pink hue. She gets two black lines running vertically down her body. This indicates that the female is attracted by the male and is ready for breeding. She shows her affection by opening her fins and moving it towards the male.

After the fertilization embrace, the female expels the eggs. Male anatomy has a significant impact in ensuring that all of the eggs are successfully fertilized. During embrace, the male's broad anal fin serves as a landing platform for the let-down eggs.

The female emerges first and begins collecting the eggs that have fallen on the male's anal fin. Unlike other bettas, Betta Macrostoma follow Oral Incubation. After collecting the eggs in her buccal cavity, the female approaches the male. The female spits out the eggs one by one and the male collects them in his mouth. This is not a onetime procedure.

The female may spit out the eggs several times before they are transferred into the male's mouth. This process is referred to as Oral Incubation. The eggs are sometimes swallowed by the male during this procedure. They do, nevertheless, reunite for breeding in a week or two. It's always better to transfer the female fish out of the breeding tank after oral incubation, as she has a high probability of re-entering the spawning stage again.

The male may carry the fry for 14-17 days or more. When the fry is released, they are already developed, swimming freely, and larger in size than typical betta fry from other species complexes. It's now time to relocate the male away from the fries. At this stage it is best to clean the tank as the water quality is likely to have deteriorated due to the spawning process.

How to Look After Male Betta After the Breeding Procedure?

After mating or breeding, male Betta Macrostoma become highly vulnerable. Their color fades and their fins become tattered. It is recommended that you feed them high quality Betta fish food.

They are not picky eaters, so finding the ideal food shouldn't be difficult. Pinhead crickets, Wingless fruit flies, Daphnia, while worms, Grindal worms, Peanut beetles, Frozen bloodworms, Frozen Mysis shrimps, Frozen Artemia, Frozen glassworms, Krill, Earthworms, Dried bloodworm, pellet food will all be an excellent food for Betta Macrostoma post-breeding.


What Other Names Does the Betta Macrostoma Go by?

They are also known as Brunei Beauty and Spotfin Betta

Where Does Betta Spotfin Macrostoma Originate From?

Betta Macrostoma originated from Brunei, Malaysia.

How Big Are Betta Macrostoma?

Betta Macrostoma grows up to 4.5-5 inches in length.

How Long Do Betta Macrostoma Live?

Betta Macrostoma has a life span of 3-5 years.

What Type of Water Does Betta Macrostoma Prefer?

These fishes prefer still, slightly acidic waters with a temperature of 70-75°F.

How to Tell the Difference Between a Male and a Female Betta Macrostoma?

The biggest difference between the male and the female, is that the males are bright orange in color, while the females are darker. Also, the female's anal fin will have two black lines running vertically down her body and the male has a broad anal fin which helps him to collect the eggs when they spawn.

Can Betta Macrostoma Be Put Together With Other Fish?

Betta Macrostoma can be put together with the same kind of Betta only, as they are very territorial.

How Do I Adjust the Water Ph to Make It More Acidic for My Betta Macrostoma?

Adding peat moss to the water or leaving water out for a few days will raise the ph.

How Large of a Tank Does Betta Macrostoma Require?

Betta Macrostoma requires an aquarium of not less than 10 gallons.

What Temperature Should Be Kept for My Betta Macrostoma?

Betta Macrostoma prefer temperatures ranging from 70-75°F.

How Often Should Water in the Tank Be Changed for My Betta Macrostoma?

Water should be replaced with de-chlorinated water every week.

What Type of Food Should I Feed My Betta Macrostoma?

Foods such as pellets, flakes, live bloodworms, brine shrimp, black worms, and other small insects can be fed to the Betta Macrostoma.

Will My Betta Macrostoma Eat Other Fish in the Tank?

Betta Macrostoma will eat other fish that are small enough for them to swallow whole.

Can I Put Peat Moss in My Betta's Tank?

Yes, adding peat moss will help to raise the acidity level in your Betta's tank.

Does Betta Macrostoma Need to Be in a Pair?

No, Betta Macrostoma will do well by themselves.


Betta Macrostoma, like any other bettas, can be a challenging fish to take care of. This is because of its sensitive nature and their temperament which require proper care and management. They are happiest in larger tanks.

This fish should be kept in an aquarium with at least 20 gallons of water and a temperature of 70°F (21-26°C). They like a pH level of 6.0 to 7.0, so use hard or very slightly hard water. They are tropical fishes and have a lifespan of 3-5 years.  Betta Macrostoma are rather mild-mannered and can be kept together with their own kind if the tank is big enough.

However, do note that this species will eat any other fish that are small enough to be swallowed whole. Most of all, these bettas require clean water on a weekly basis. It is also important to provide them with nutritious food and create a suitable environment for them to grow in.

It's an extremely rare fish in the United States, and it's quite uncommon elsewhere. So, if you come upon one at your local pet store or aquarium shop, grab it! To sum up, this may be the pet for you if you have the time, space, money, and knowledge to care for Betta Macrostoma.

Sarah Robertson

I am a passionate blogger who also happens to be a fish keeping enthusiast. Writing about my hobby is something that I absolutely love to do, and it's no secret that my chosen topic is always centered around fish keeping.

Sarah Robertson

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